Knotless bioabsorbable suture anchor system and method

ABSTRACT

A knotless suture system for anchoring tissue to bone is provided. The system includes a suture anchor configured to radially expand into bone. The suture anchor has a proximal end and a distal end with a bore formed therein. The system further includes a first loop of suture thread attached to the distal end of the suture anchor, a suture needle, and a second loop of suture thread attached to the needle and interlocked with the first loop of suture thread. The system also includes an expander pin that is configured and sized for insertion into the bore of the suture anchor, causing the anchor to radially expand from a first outer diameter to a second outer diameter. A method is also provided by which a detached tissue may be securely attached to bone in an anatomically correct position without the need to tie a knot.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

1. Field of the Invention

The invention relates generally to medical devices and procedures. Moreparticularly, this invention relates to a knotless bioabsorbable sutureanchor system for attaching soft tissue to bone, and to methods forattaching soft tissue to bone.

2. Background of the Invention

Soft tissues, such as ligaments, tendons and muscles, are attached to alarge portion of the human skeleton. In particular, many ligaments andtendons are attached to the bones which form joints, such as shoulderand knee joints. A variety of injuries and conditions require attachmentor reattachment of a soft tissue to bone. For example, when otherwisehealthy tissue has been torn away from a bone, surgery is often requiredto reattach the tissue to the bone to allow healing and a naturalreattachment to occur.

A number of devices and methods have been developed to attach softtissue to bone. These include screws, staples, cement, suture anchors,and sutures alone. Some of the more successful methods involve the useof a suture anchor to attach a suture to the bone, and tying the suturein a manner that holds the tissue in close proximity to the bone.

The tissue may be attached to the bone during open surgery, or duringclosed (e.g., arthroscopic) surgical procedures. Closed surgicalprocedures are preferred since they are less invasive and are lesslikely to cause patient trauma. In a closed surgical procedure, thesurgeon performs diagnostic and therapeutic procedures at the surgicalsite through small incisions, called portals, using instrumentsspecially designed for this purpose. One problem encountered in the lessinvasive, closed surgical procedures is that the surgeon hassignificantly less room to perform the required manipulations at thesurgical site. Thus, devices and methods are needed which will allow asurgeon to effectively and easily attach tissue to bone in the smallspaces provided by less invasive surgical procedures.

Conventional methods for attaching soft tissue to bone typically requirethat the surgeon tie a knot in the suture thread to attach the suture toan anchor, or to attach the tissue to the bone using the suture. Knottying at the surgical site in closed surgical procedures, and even inopen surgery, is difficult and time consuming due to inherent spaceconstraints. Further, knots and other bulky attachment means canirritate tissue over time.

Knotless suture anchor systems have been developed for use with closedsurgical procedures, and U.S. Pat. No. 5,569,306 provides one example ofsuch a system. Although generally useful, such systems can be limited touse only with certain types or shapes of tissue, or to use with certainanatomical structures. Proper attachment of soft tissue requires that itbe placed in the anatomically correct position to promote optimalhealing.

A further knotless suture anchor system is disclosed in U.S. Pat. No.5,782,864. While useful, the suture anchor and system disclosed in thispatent is not believed to be absorbable. That is, the suture anchor ismade of a metal, which will remain permanently implanted in the patient.

Further, some conventional knotless suture anchor systems may require,in order to attach a broader array of tissue shapes to bone, that thesuture anchor pass though the tissue to be attached. This is undesirablebecause it unnecessarily irritates the injured tissue and it requiresopening a much larger hole in the tissue.

There is thus a need for an improved system for anchoring soft tissue tobone which reduces or eliminates the need to tie suture knots at thesurgical site. Further, there is a need for an improved system foranchoring soft tissue to bone which is fast and easy to deploy. It wouldalso be advantageous to provide at least a partially absorbable knotlesssuture anchor and system so as to encourage natural regrowth of thedamaged or torn tissue.

SUMMARY OF THE INVENTION

The present invention provides a knotless suture system for anchoringtissue to bone. The system includes a suture anchor configured toradially expand into bone. The suture anchor has a proximal end and adistal end with a bore formed therein. The system further includes afirst loop of suture thread attached to the distal end of the sutureanchor, a suture needle, and a second loop of suture thread attached tothe needle and interlocked with the first loop of suture thread. Thesystem also includes an expander pin that is configured and sized forinsertion into the bore of the suture anchor, causing the anchor toradially expand from a first outer diameter to a second outer diameter.A method is also provided by which a detached tissue may be securelyattached to bone in an anatomically correct position without the need totie a knot.

In one embodiment, the system includes a suture anchor having proximaland distal ends, wherein a suture-engaging tip is present at the distalend and a separate, radially expandable sleeve, having a bore formedlongitudinally therethrough, forms a proximal end of the suture anchor.The tip and the sleeve are mated to one another, such as by a threadedengagement. The system further includes an expander pin for insertioninto the bore of the expandable sleeve. In this embodiment, theexpandable sleeve may include two substantially flat, opposed sidesbetween the proximal and distal ends and separated by the bore. As notedabove, the system includes a first loop of suture thread attached to thetip, a second loop of suture thread interlocked with the first loop, anda suture needle having a first, tissue penetrating end and a second,trailing end attached to the second loop. In one embodiment, theexpander pin is made from a bioabsorbable material.

In another embodiment, the system comprises a suture anchor whichincludes a unitary base member having a distal end and a proximal endwith a bore formed longitudinally therein, and a separate expander pinfor insertion into the bore of the base member to effect radialexpansion of at least a portion of the base member. The distal end ofthe base member has a suture thread-engaging groove for seating aportion of the first loop of suture thread. Additionally, the basemember can have two substantially flat, opposed sides between the distaland proximal ends to allow suture thread to easily pass around the basemember. The flat sides can each contain a longitudinally oriented slit,which may be matable with the protrusions on opposite sides of theexpander pin. Preferably, the base member and expander pin are formedfrom a bioabsorbable material.

In an embodiment that is particularly useful in closed surgery, thesecond suture loop is formed using a suture loop closure and is attachedto a hollow suture needle by means of a slot provided in a wall of thehollow needle. This embodiment may also employ an actuator, disposedwithin the hollow needle, which can be selectively deployed to disengagethe second suture loop from the needle. The hollow needle used with thisembodiment preferably is part of an elongate tool, such as a sutureinserter, that is useful in closed surgical procedures. The hollowneedle typically forms the distal end of such a tool.

Various types of inserter tools are also included with the system of theinvention. The inserter tool generally includes an elongate shaftelement, and a pusher or actuation element may be slidably mounted onthe shaft Actuation of the pusher causes the expander pin to be disposedwithin the bore of the radially expandable sleeve or proximal componentof the anchor to effect radial expansion.

The system may be used in a method wherein the suture needle and theattached second suture loop are passed through a detached segment oftissue. The second suture loop is pulled through the detached tissueuntil a portion of the interlocked first suture loop extends through thedetached tissue. The suture anchor is then maneuvered so that a portionof the first suture loop is seated within a suture-engaging groove atthe distal end of the suture anchor. The anchor is then inserted into apredrilled bore in a portion of bone. Once the suture anchor is insidethe bone, the expander pin is driven into the bore of the suture anchor,expanding the base radially to the extent that external walls of thesuture anchor engage bone. The suture anchor is stabilized in a frictionfit within the bore, and the detached tissue is thereby attached to thebone in the desired position.

The term “suture needle” is used herein to encompass both conventionalsuture needles, used in open surgical procedures, as well as sutureneedles that may form a hollow, distal end of an elongate tool usefulwith closed surgical procedures.

Further features of the invention, its nature and various advantages,will be more apparent from the accompanying drawings and the followingdetailed description of the drawings and the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary suture anchor system of theinvention attached to a portion of an inserter tool;

FIG. 2 is a cross-sectional view of the suture anchor system of FIG. 1;

FIG. 2A is an exploded view of the suture anchor system of FIG. 2;

FIG. 3 is a perspective view of another exemplary suture anchor systemof the invention attached to a portion of an inserter tool;

FIG. 4 is a cross-sectional view of the suture anchor system of FIG. 3;

FIG. 4A is an exploded view of the suture anchor system of FIG. 4;

FIG. 5 is a partial view of a second suture loop with a suture loopclosure;

FIG. 6 is a partial view of the second suture loop and suture loopclosure of FIG. 5 engaged with a suture needle;

FIG. 7 is a view of a bore being drilled in bone for receiving a sutureanchor system;

FIG. 8 is a view of a portion of the suture anchor system engaged with adetached tissue;

FIG. 9 is a view of the detached tissue with the second suture loopextending therethrough;

FIG. 10 is a view of a portion of the suture anchor system of FIG. 1before the suture anchor is inserted into a bone;

FIG. 11 is a view of a portion of the suture anchor system of FIG. 1showing the first suture loop being engaged;

FIG. 12 is a view of a portion of the suture anchor system of FIG. 1with the suture anchor inserted into a bone;

FIG. 13 is a cross-sectional view of a portion of the suture anchorsystem of FIG. 12; and

FIG. 14 is a cross-sectional view of a tissue attached to a bone, and afully seated suture anchor, using the system and method of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 through 2A, a system for anchoring tissue tobone in accordance with the invention is shown. The system 10 includes asuture anchor 12 configured to radially expand into bone. The sutureanchor 12 has a proximal end 14 and a distal end 16 having a bore 22that extends along a longitudinal axis 18 thereof. The suture anchor 10includes a suture-engaging tip 40 at the proximal end 14 and a separate,radially expandable sleeve 20 at the distal end 16. The system of FIG. 1also includes a first suture loop 80 attached to the suture-engaging tip40, a suture needle 90, and a second suture loop 82 attached to thesuture needle 90. The first suture loop 80 and second suture loop 82 areinterlocked with each other. The system also includes an expander pin 60that is configured and sized for insertion into the bore 22 of theexpandable sleeve 20, causing the suture anchor 10 to radially expandfrom a first diameter to a second diameter.

The sleeve 20 is attached to the suture-engaging tip 40 and forms theproximal end 14 of the suture anchor 10. The expandable sleeve 20 caninclude two substantially flat, longitudinally extending portions 24, 28formed on opposite sides of the sleeve 20, between the proximal end 14and distal end 16 of the sleeve 20, to allow for suture thread to easilypass back and forth. Although sides 24, 28 are shown as flat, it isunderstood that they may be otherwise shaped or contoured. For example,they may be curved or rounded. The sides 26, 30 that are adjacent tosides 24, 28 may be curved, rounded, or flat.

Suture engaging tip 40 includes at a distal end a suture-thread engaginggroove 42, and intermediate the distal and proximal ends of the tip 40is a through hole 44 for attaching suture thread. Suture-engaging groove42 is configured for seating a portion of the first loop 80. The tip 40is preferably mated to the sleeve 20. Preferably, as shown in FIG. 2,tip 40 is threadingly engaged to the distal end 16 of expandable sleeve20. As illustrated, a proximal end of tip 40 includes an externalthreaded region 46 and a distal end of the sleeve 20 includes acomplementary internal threaded region 32 which is sized and shaped tomatingly receive the threaded portion 46 of tip 40. Although FIG. 2illustrates external threads 46 on tip 40 mating with internal threads32 of the sleeve 20, one of ordinary skill in the art will appreciatethat other configurations may be used as required.

As further shown in FIGS. 1 and 2, the system includes an expander pin60 configured and sized to be inserted into the bore 22 of the sleeve 20in an interference fit. Expander pin 60 has an outer diameter which isslightly larger than the inner diameter of bore 22. When expander pin 60is fully seated within bore 22, the expandable sleeve 20 radiallyexpands so as to engage the walls of the bore. The radial expansion ofthe sleeve 20 causes the sleeve to transition from a first diameter to asecond, larger diameter. The difference between the first and seconddiameters is generally in the range of about 1.0 mm to 1.5 mm.

The expandable sleeve 20 preferably includes one or more externalsurface features 34 that enhance the bone engaging properties of thesleeve 20. As shown in detail in FIG. 2A, the external surface features34 may be in the form of several, adjacent ramped ridges 36. Each ridgehas a distal portion 37 and a raised, proximal portion 39. The surfaceconnecting the distal and proximal portions 37, 39 of each ridge 36preferably is a continuous surface 38 that is disposed at an angle withrespect to longitudinal axis 18 in the range of about 9 to 11 degrees.In one embodiment, the difference in height between the distal andproximal portions 37, 39 of each ridge 36 is in the range of about 1.4to 0.75 mm. The distal facing surface 38 of each ridge 36 is in the formof an endwall that is preferably oriented to be substantiallyperpendicular to the longitudinal axis 18 of the suture anchor 10. It isunderstood, however, that the endwall may be slightly overcut orundercut.

In the illustrated embodiment, the sleeve 20 has approximately eightridges 36. It is understood that as few as one or two ridges may bepresent, and that more than eight ridges may be present.

The expansion pin 60 also has one or more positive surface features 62formed on an external surface 64 thereof. The surface features arepreferably wedge-like fins 68, or tapered ridges, that arenon-deformable.

Each wedge-like fin 68 of the expansion pin 60 has a ramped surfacewhich increases in height from a distal end 69 to a proximal end 71thereof. The surface 70 connecting the distal and proximal ends 69, 71is continuous and is preferably oriented at an angle (with respect tolongitudinal axis 18) in the range of about 15 to 17 degrees. Thedifferential in height between the distal end 69 and the proximal end 71of each fin 68 is in the range of about 1.5 to 1.6 mm.

As illustrated in FIGS. 1 through 2A, the fins 68 are disposed on theexpansion pin 60 adjacent to one another. The expansion pin 60 mayinclude a single fin or it may have several. As shown in FIG. 2, one ormore fins may have an extended distal end. For example, fin 68′ includesan extended distal surface 76 that runs parallel with longitudinal axis18 over a distance of about 0.4 to 0.6 mm.

The distal facing surface 76 of each fin 68, 68′ is in the form of anendwall that is preferably oriented to be substantially perpendicular tothe longitudinal axis 18 of the suture anchor. It is understood,however, that the endwall may be slightly overcut or undercut.

The suture anchor 12 may be constructed from suitable materials known tothose of ordinary skill in the art. In one embodiment, expandable sleeve20 is constructed from a polymeric material that is substantially rigid,yet able to withstand a force that expands the diameter of the sleeve 20by about 30% without failing. Examples of suitable materials includehigh density polyethylene and polypropylene. Tip 40 is constructed froma suitable metal such as medical grade stainless steel or titaniumalloy. Alternatively, tip 40 can be constructed from a polymer such aspolylactic acid or polysulfone. Expander pin 60 is preferably formedfrom a bioabsorbable material, such as polylactic acid (PLA) andpolysulfone.

The system may also include an anchor insertion tool of the typecommonly used in the art. A portion of an insertion tool 200 suitablefor deployment of the suture anchor 10 of this invention is illustratedin relevant part in FIGS. 1 and 2. Insertion tool 200 includes a distalend 202 having a tip 206 with an external threaded portion 208 which issized and shaped to matingly engage with the internal threaded portion50 of tip 40. As shown in FIG. 2, tip 40 includes a bore 48 having aninternal threaded portion 50 therein which is adapted to mate with theexternal threaded portion 208 of the tool 200. In some embodiments, thesuture anchor 10 may be removably premated to the distal end 202 of theinsertion tool 200.

The insertion tool 200 also includes an elongate shaft 214 that isproximal of the distal end 202. The shaft 214 is adapted to receive theexpandable sleeve 20 and the expander pin 60 in a clearance fit. Asshown in FIG. 2, an annular gap 52 is present between the outer surface215 of the shaft 214 and an inner surface 21 of the sleeve 20. Theexpander pin 60, which is mounted on the shaft 214 proximally adjacentto and abutting sleeve 20, is also mounted on the shaft 214 in aclearance fit that enables the expander pin 60 to slide distally on theshaft 214 to occupy and expand the gap 52. A pusher member 210 may bemounted on the shaft 214 proximally adjacent to a distal end 72 ofexpander pin 60. The distal end 218 of the pusher member 210 includes aface 220 that abuts the expander pin 60, transferring a force theretothat permits the expander pin 60 to slide within gap 52. One of ordinaryskill in the art will appreciate the force necessary to move the pushermember 210 and the expander pin 60 distally may be provided by a varietyof mechanisms that are known in the art.

The gap 52 preferably has dimensions in the range of 0.2 to 0.4 mmbefore being expanded by the action of expander pin 60. As illustratedin FIG. 2A, the diameter of the expander pin 60 at a distal (smallest)end (D_(EP1)) of wedge-like fins 68 is preferably about equal to innerdiameter (ID_(S)) of sleeve 20. The diameter of the expander pin 60 atits widest dimension (D_(EP2)), measured at the distal ends 69 ofwedge-like fins 68, is in the range of about 4.0 to 4.2 mm. Thus, as theexpander pin 60 is forced into gap 52, the sleeve 20 radially expandsfrom a first outside diameter (OD₁) to a second outside diameter (OD₂).

One of ordinary skill in the art will readily appreciate that thedimensions of the various components of the system 10 may vary dependingupon the desired surgical applications. Generally, however, theexpandable sleeve 20 has a length of about 10 to 20 mm and a first outerdiameter (OD₁) of about 4.5 to 4.7 mm. The outer diameter (OD₁) of thesleeve 20 will increase during use to a second outer diameter (OD₂),discussed above, to about 5.5 to 6.0 mm. The expander pin 60 preferablyhas a length in the range of about 5 to 15 mm. The tip 40 preferably hasa length in the range of about 5.0 to 6.0 mm.

As noted above, the tool 200 includes a distal end 202 with externalthreads 208 that mate with the internal threads 50 of the tip 40. Thisarrangement firmly secures the suture anchor 10 to the tool 200. Thus,when the pusher member 210 is actuated, moving expansion pin 60distally, the suture anchor 12 is not able to move distally. As force iscontinued to be applied by the pusher member 210, the expansion pin 60moves into the gap 52 between the shaft 214 and the internal surface 21of the sleeve 20. This causes radial expansion of the sleeve 20. Whenthe expander pin 60 is securely positioned inside the bore 22 of thesleeve 20, the tool can be removed by unscrewing the threaded portion208 of the tip 206 of tool 200 from the internal threads 50 of the tip40.

In another embodiment, the suture anchor can be formed from a singlepiece of material. For example, FIGS. 3 and 4 show another exemplaryembodiment wherein the system 100 includes a suture anchor 110 comprisesa unitary expandable base member 112. Expandable base member 112 issimilar to expandable sleeve 20 of suture anchor 10, and includessimilar elements, which are designated with the prefix “1” (e.g.,through hole 44 of suture anchor 12 is designated through hole 144 forsuture anchor 110). Key features and distinctions are highlightedhereinbelow.

As shown in FIGS. 3 through 4A, suture anchor 110 includes an expandablebase member 112 having a proximal end 114 and a distal end 116. Theproximal end 114 has a bore 122 extending longitudinally therethrough.The distal end 116 of base member 112 includes a suture thread-engaginggroove 142. The system 100 used with suture anchor 110 and illustratedin FIG. 3 also includes a first suture loop 80 attached to the distalend 116 of the expandable base member 112 by a through hole 144, asuture needle 90, and a second suture loop 82 attached to the sutureneedle and interlocked with the first suture loop 80. Suturethread-engaging groove 142 is configured for seating a portion of thefirst loop 80. The system 100 also includes an expander pin 160 that isconfigured and sized for insertion into the bore 122 of the expandablebase member 110, causing the suture anchor 100 to radially expand from afirst diameter to a second diameter.

The expandable base member 112 can include two substantially flat,longitudinally extending portions 124, 128 formed on opposite sides ofthe base member 112 to allow for suture thread to easily pass back andforth. Although sides 124, 128 are shown as flat, it is understood thatthey may be otherwise shaped or contoured. For example, they may becurved or rounded. The sides 128, 130 that are adjacent to sides 124,128 may be curved, rounded, or flat.

In addition, sides 124, 128 may include slits 104 that will allow foreasy expansion of the anchor base 110. As shown in FIG. 4, the expansionpin 160 of this system includes complementary protrusions 106 on opposedsides which are sized and shaped to matingly engage and seat within theslits 104 of the base member 112 when fully inserted into the bore 122.Preferably, the protrusions 106 irreversibly interlock with slits 104.

As further shown in FIGS. 3 and 4, the system includes an expander pin160 configured and sized to be inserted into the bore 122 of theexpandable base member 112 in an interference fit. Expander pin 160 hasan outer diameter which is slightly larger than the inner diameter ofbore 122. In one embodiment shown in FIGS. 4 and 4A, the outer surfaceof expander pin 160 tapers from the proximal end 174 to the distal end172 such that, from a cross-sectional view, the expander pin 160 has aflared, proximal end.

When expander pin 160 is fully seated within bore 122, the expandablebase member 112 radially expands so as to engage the walls of the bore.The radial expansion of the base member 112 causes the anchor 100 totransition from a first diameter to a second, larger diameter. Thedifference between the first and second diameters is generally in therange of about 1.0 mm to 2.0 mm.

The expandable base member 112 preferably includes one or more externalsurface features 134 that enhance the bone engaging properties of thebase member 112. The external surface features 134 may be in the form ofseveral, adjacent ramped ridges 136, similar to the ridges 36 of anchor10 that are described above.

The expansion pin 160 also has one or more positive surface featuresformed on an external surface thereof (not shown). The surface featuresare preferably wedge-like fins, or tapered ridges, that arenon-deformable. The wedge-like fins are similar to fins 68 of anchor 10that are described above.

The suture anchor 110 and system 100 may be constructed from suitablematerials known to those of ordinary skill in the art. In oneembodiment, expandable base member 112 is constructed from a polymericmaterial that is substantially rigid, yet able to withstand a force thatexpands the diameter of the base member 112 by about 30% withoutfailing. Preferably, expandable base member 112 and expander pin 160 areformed from a bioabsorbable material, such as polylactic acid (PLA) andpolysulfone.

FIG. 4 shows a cross-sectional view of the suture anchor 110 and system100 attached to a portion of the exemplary insertion tool 200 describedabove. As shown, expandable base member 112 includes a bore 122 havinginternal threads 150 formed therein, which are adapted to mate with theexternal threaded portion 208 of the tool 200. In some embodiments, thesuture anchor 100 may be removably premated to the distal end 202 of theinsertion tool 200. Although FIG. 4 illustrates external threads 208 ontip 206 mating with internal threads 150 of the base member 112, one ofordinary skill in the art will appreciate that other configurations maybe used as required. In some embodiments, the suture anchor 100 may beremovably premated to the distal end 202 of the insertion tool 200.

As shown in FIG. 4, the shaft 214 of insertion tool 200 is adapted toreceive the expandable base member 112 and the expander pin 160 in aclearance fit. An annular gap 152 is present between the outer surface215 of the shaft 214 and an inner surface 121 of the base member 112.The expander pin 60, which is mounted on the shaft 214 proximallyadjacent to and abutting base member 112, is also mounted on the shaftin a clearance fit such that the expander pin 160 is able to slidedistally on the shaft 214 to occupy and expand the gap 152. A pushermember 210 may be mounted on the shaft 214 proximally adjacent to adistal end 172 of expander pin 160. The distal end 218 of the pushermember 210 includes a face 220 that abuts the expander pin 160,transferring a force thereto that permits the expander pin 160 to slidewithin gap 152. One of ordinary skill in the art will appreciate theforce necessary to move the pusher member 210 and the expander pin 160distally may be provided by a number of mechanisms that are known in theart.

In use, the first suture loop 80 may be suitably attached to the sutureanchor 12, 110 through one or more through holes 44, 144 that are formedin the body of the suture anchor 12, 110, and which extend transverselyto longitudinal axis 18. In the exemplary suture anchors 12, 110, thefirst suture loop 80 is attached substantially at distal ends 16, 116 ofthe anchor 12, 110, and portions of first suture loop 80 extend past theproximal ends 14, 114 on opposed sides of the suture anchor 12, 110.

Through hole 44, 144 is adapted, by providing varying diameters withinthe through hole 44, 144, to retain the first suture loop 80. Forexample, the diameter within the hole 44 can be varied by providing anannular collar (not shown) therein. The inner diameter of the annularcollar can be large enough to allow the unknotted portion of the firstsuture loop 80 to pass through the inner diameter. However, the innerdiameter is small enough to prevent the knot from passing through thethrough hole 44, 144. When the unknotted portion of the first sutureloop 80 is drawn through the hole 44, 144 the knot is retained by theannular collar and the first suture loop 80 is thereby attached to thetip 40.

The first suture loop 80 may be attached to the suture anchor by tyingtwo free ends of a suture thread into a knot (not shown). It will beunderstood that one may use other methods of attaching the two freeends, including the use of suture loop closure devices as furtherdescribed below with regard to the second suture loop.

The first suture loop 80 may be constructed from thread suitable for useas a suture. A variety of suture materials are well known to those ofordinary skill in the art. Exemplary materials include braided polyesterand polydioxanone (PDS).

The length of the first suture loop 80 may be determined by a person ofordinary skill in the art, depending upon the desired applications ofthe system. This dimension depends, to a large extent, upon thedimensions of the tissue to be attached, the type of surgery to beperformed, and whether an open or closed surgical technique is to beused. By way of example, the length of the first suture loop may rangefrom about one quarter to one and one half inch in procedures to repaira Bankart lesion or a rotator cuff tear. In an exemplary embodiment, asused in the method described herein below, the length of the firstsuture loop 80 is about one half inch.

Referring again to FIG. 1, the suture needle 90 has a first, tissuepenetrating end 92 and a second trailing end 94. The size and shape ofthe needle used with the system of the invention may be selected by aperson of ordinary skill in the art depending upon the specificapplication of the system, and in particular, depending upon whether thesystem is used in an open or closed (e.g., arthroscopic) surgicalprocedure. Generally, needle 90 is at least slightly curved.

In the exemplary embodiment of FIG. 1, which is typically used in opensurgical procedures, the second suture loop 82 is attached to the sutureneedle 90 at the second end 94 of needle 90. One of ordinary skill inthe art will appreciate that a number of techniques can be utilized tojoin the second suture loop 82 to the suture needle 90. For example, thesecond end 94 of the suture needle 16 can be hollowed so that two freeends of suture thread may be inserted therein. The hollowed end is thencrimped to securely retain the two ends of suture thread within thesecond end 94 of the needle 90, thus creating the second suture loop 18.

In an alternative embodiment, shown in FIGS. 5 and 6, that isparticularly suited for use in closed surgical procedures the secondsuture loop 82 may be attached to the needle 90 a by means of a sutureloop closure 96. Referring now to FIG. 5, the second suture loop 82 maybe formed by attaching two free ends of a length of suture thread withina suture loop closure 96. The suture loop closure 96 may consist of ametal tube having an internal diameter large enough to admit two ends ofsuture thread. The two free ends of the suture thread are then enteredinto the suture loop closure 96 and the suture loop closure 96 iscrimped to retain the ends of the suture thread and form the secondsuture loop 82. It will be understood that the suture loop closure 96may take other forms, including a knot tied with the two free ends ofthe suture thread.

A second suture loop 82, having a suture loop closure 96, may beattached to a suture needle 90 a as shown in FIG. 6. In this exemplaryembodiment, the suture needle 90 a is a hollow member, having an opendistal end 94, one wall of which includes a tissue-penetrating edge orpoint 92. A slot 98 is formed in the wall of the distal end of theneedle, preferably opposite point 92. The slot 98 has an open end 97that communicates with the open distal end 94 of the suture needle 90and an opposite, closed end 99. The slot 98 is wide enough to slidablyengage the second suture loop 82, but narrow enough to retain the sutureloop closure 96 on one side of the slot 98. The second suture loop 82 isthen attached to the suture needle 90 a by placing the suture loopclosure 96 inside the open first end 97 of the hollow suture needle 90 aand sliding the suture loop closure 96 and the attached second sutureloop 82 within the slot 98 to the closed end 99 thereof.

The hollow suture needle 90 a of FIG. 6 may also include an internallydisposed actuator 88. The actuator 88 may be a rod that is selectivelyslidable within the hollow suture needle 90 a between a first position,in which the actuator 88 is inside the hollow needle 90 a and does notreach the slot 98, and a second position (not shown), in which theactuator 88 extends past the slot 98. Selectively sliding the actuator88 from the first position to the second position causes the actuator 88to contact the suture loop closure 96 (and the attached second sutureloop 82), causing closure 96 to slide the length of slot 98 and becomedisengaged from the needle 90.

Suture needle 90 a, as noted above, is well suited for use in closedsurgical procedures. The suture needle 90 a may form the distal end ofan elongate suture inserter tool (e.g., an arthroscopic, laparoscopic orendoscopic tool) that is useful in closed surgical procedures.

The second suture loop 82, like the first suture loop 80, may beconstructed from well known materials suitable for use as a suture. Thelength of the second suture loop may be determined by a person ofordinary skill in the art depending upon factors such as the dimensionsof the tissue to be attached, the type of surgery to be performed, andwhether an open or closed surgical technique is to be used. For example,the length of second loop 82 is generally in the range of about 20 to 40inches, and more preferably about 30 to 36 inches for closed surgicalprocedures. Open surgical procedures can utilize a smaller length forsecond loop 18, in the range of about 6 to 12 inches and more preferably8 to 10 inches.

The systems 10, 100 of the invention for anchoring tissue to bone may beused in the method described herein below. For purposes of illustration,FIGS. 7-14 depict the method of using suture anchor 12 in the context ofarthrosporic shoulder repair, more specifically, attaching a detachedlabrum (as might result from a Bankart lesion or rotator cuff tear) tothe glenoid rim of a scapula. It will be understood, however, that thesystem and method described herein are equally applicable to connectingdetached tissue in other contexts as well. Further, the method describedis merely exemplary of the steps involved in both systems and is equallysuitable for the system 100 of suture anchor 110 as well.

Referring to FIG. 7, a bore 520 is formed in a bone 540. The diameter ofthe bore 520 should be slightly larger than the outer diameter of thesuture anchor 12. In an exemplary embodiment, the diameter of the bore520 is approximately 3.5 to 4.7 mm when the outer diameter of the anchor12, 110 is about 4 mm. It is contemplated that the outer diameter of thesuture anchor 12, 110 will increase about 1.0 mm when fully expanded.The length of the bore must be of sufficient length to allow forcomplete seating of the suture anchor 12, 110, and to enable the depthof the anchor to be adjusted to help control the tightness of the firstsuture loop 80. The actual length of the bore 520 will depend upon thelength of the first suture loop 80 and the thickness of the detachedtissue 560.

As shown in FIG. 8, the suture needle is then passed through thedetached tissue 56. The suture needle 90 and the attached second sutureloop 82 are pulled through the detached tissue 560 to advance theinterlocked first loop 80 through the tissue, as illustrated in FIG. 9.If the procedure is being performed arthroscopically, the suture needle90 a and the tool with which it is associated will be pulled from, andexit through, an exit portal (not shown).

Alternatively, in embodiments that utilize the needle 90 a, shown inFIG. 6, the needle 90 a may penetrate the detached tissue 560. Theactuator 48 is then selectively moved so as to disengage the suture loopclosure 44 and the attached second suture loop 82 from the needle 90 a.The suture needle 90 a may then be withdrawn from the patient's bodyfrom the portal through which the needle entered. A suture grasper orretrograder (not shown) may be used to pull the remaining portion of thesecond loop 18 through the detached tissue 560.

In FIG. 10, the first suture loop 80 is positioned over the bore 520 bymanipulating the position of the second suture loop 82. When the firstsuture loop 80 is in its desired position, the insertion tool 200 ismaneuvered so that a portion of the first suture loop 80 is seated inthe suture-engaging groove 42 of the suture anchor 12, as shown in FIG.11. Once the first suture loop 80 is so seated, the anchor 10 is alignedwith the bore 520, and the suture anchor 12 is then inserted into thebore 520. When the suture anchor 12 is partially inserted, asillustrated in FIG. 12, the second suture loop 82 can be cut anddiscarded along with the suture needle 90.

Referring to FIG. 13, when the suture anchor 10 is advanced all the wayinto the bore 520, the pusher 210 is deployed to drive the expander pin60 into the bore 22 of the expandable sleeve 20. As the expander pin 60is inserted, the expandable sleeve 20 will radially expand, causing thesleeve 20 to wedge into the bone 540. When the expander pin 60 iscompletely inserted, as shown in FIG. 14, the expandable sleeve 20 isfully expanded and anchored in a frictional fit within the bore 520 ofthe bone. The result is a snug, anatomically correct attachment of thedetached tissue 560 to the bone 540. Once the anchor 12 is inserted intobore 520, the anchor 12 is disengaged from the insertion tool 200 andthe insertion tool 200 is removed.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. All references cited herein are expressly incorporatedby reference in their entirety.

What is claimed is:
 1. A system for anchoring tissue to bone,comprising: a suture anchor having proximal and distal ends, wherein asuture-engaging tip is present at the distal end of the anchor and aseparate, radially expandable sleeve, having a bore formedlongitudinally therein, is attached to the suture-engaging tip and formsa proximal end of the suture anchor; a first loop of suture threadattached to the suture-engaging tip; a second loop of suture threadinterlocked with the first loop of suture thread; and a suture needlehaving a first, tissue penetrating end and a second, trailing end,wherein the suture needle is attached to the second loop of suturethread.
 2. The system of claim 1, further comprising an expander pinadapted to be inserted into the bore of the sleeve to effect radialexpansion of the sleeve.
 3. The system of claim 2, wherein theexpandable sleeve has two substantially flat, longitudinally extendingportions formed on opposite sides of the sleeve, between a proximal endand a distal end of the sleeve.
 4. The system of claim 3, wherein aproximal end of the tip includes a first threaded region and a distalend of the sleeve includes a complementary threaded region, enabling thetip to be threadingly connected to the sleeve.
 5. The system of claim 4,wherein the proximal end of the tip has an internally threaded boreformed therein.
 6. The system of claim 5, wherein the first threadedregion of the tip is formed on an outer surface of the tip.
 7. Thesystem of claim 6, further comprising an elongate insertion tool havinga proximal, handle end, an externally threaded distal end that ismatable with the internally threaded bore of the tip, and a shaft thatis able to be disposed within the bore of the sleeve in a clearance fit.8. The system of claim 7, wherein the expander pin has a longitudinalbore extending therethrough from a proximal end to a distal end thereof,the longitudinal bore having an inner diameter enabling it to bedisposed on the shaft of the insertion tool in a first positionproximally adjacent to and abutting the sleeve, and selectively moveableto a second position disposed between the shaft and an inner surface ofthe sleeve in an interference fit with the sleeve.
 9. The system ofclaim 8, wherein the positioning of the expander pin in the secondposition causes the sleeve to radially expand from a first outerdiameter to a second outer diameter.
 10. The system of claim 9, whereinthe difference between the first diameter and the second diameter is inthe range of about 1.0 to 1.5 mm.
 11. The system of claim 10, whereinthe expander pin is formed from a bioabsorbable material.
 12. The systemof claim 11, wherein the pin is made from a material selected from thegroup consisting of polylactic acid and polysulfone.
 13. The system ofclaim 11, wherein the expandable sleeve is formed from a polymericmaterial.
 14. The system of claim 13, wherein the expandable sleeve ismade from a material selected from the group consisting of high densitypolyethylene and polypropylene.
 15. The system of claim 1, wherein thetip includes a suture thread-engaging groove for seating a portion ofthe first loop of suture thread.
 16. The system of claim 1, wherein theexpandable sleeve comprises at least one external surface featureeffective to enhance bone engagement.
 17. The system of claim 16,wherein the at least one surface feature comprises a plurality ofridges.
 18. The system of claim 10, wherein the expander pin includes atleast one surface feature effective to assist in the radial expansion ofthe sleeve.
 19. The system of claim 18, wherein the at least one surfacefeature of the expander pin comprises a plurality of tapered ridgeswherein a diameter of the expander pin at a distal part of the ridge issmaller than a diameter of the expander pin at a proximal part of theridge.
 20. A system for anchoring tissue to bone, comprising: anexpandable base member having a distal end and a proximal end, theproximal end having a bore extending longitudinally therein and at leastpart of the proximal end being selectively radially expandable; a firstloop of suture thread attached to the base member; a second loop ofsuture thread interlocked with the first loop of suture thread; a sutureneedle having a first, tissue penetrating end and a second, trailingend, wherein the suture needle is attached to the second loop of suturethread; and an expander pin, selectively disposable within the bore ofthe base member to radially expand the base member from a first outerdiameter to a second outer diameter.
 21. The system of claim 20, whereinthe distal end of the base member includes a suture thread-engaginggroove.
 22. The system of claim 20, wherein the proximal end of the basemember includes two opposed sides, each having a longitudinallyextending slit formed therein.
 23. The system of claim 22, wherein thetwo opposed sides are substantially flat.
 24. The system of claim 22,wherein the proximal end of the base member has two opposed, radiallyexpandable sides, the radially expandable sides being adjacent to thetwo opposed sides.
 25. The system of claim 24, wherein the two opposedradially expandable sides each have at least one bone engaging positivesurface feature formed therein.
 26. The system of claim 25, wherein thebone engaging positive surface feature is a ridge having a distallyfacing ramped surface and a proximally facing surface with an end wallthat is substantially perpendicular to a longitudinal axis of the memberbase.
 27. The system of claim 26, wherein the expander pin includeswedge-like positive surface features effective to interact with thelongitudinally extending slits of the base member to radially expand theproximal end of the base member.
 28. The system of claim 20, wherein thebore of the base member has internal threads formed at a distal portionof the bore.
 29. The system of claim 28, further comprising an elongateinsertion tool having a proximal, handle end, a distal end with externalthreads formed therein, wherein the external threads are complementaryto the internal threads of the base member, and a shaft that is able tobe disposed within the bore of the base member in a clearance fit. 30.The system of claim 29, wherein the insertion tool further includes apusher member slidably mounted around the shaft, the pusher memberhaving a distal end proximally adjacent to and abutting a proximal endof the expander pin, such that the pusher member can be selectivelyadvanced to be positioned between the shaft and an inner surface of theproximal end of the base member to effect the radial expansion of thebase member.
 31. The system of claim 30, wherein the difference betweenthe first diameter and the second diameter is in the range of 1.0 to 1.5mm.
 32. The system of claim 27, wherein the longitudinally extendingslits of the base member have a shape complementary to the wedge-likepositive surface features of the expander pin and a size sufficient toreceive the wedge-like positive surface features.
 33. The system ofclaim 32, wherein positioning the expansion pin within the base membercauses an irreversible interlocking of the wedge-like positive surfacewithin the longitudinally extending slits.
 34. The system of claim 20,wherein the base member is formed from a bioabsorbable material.
 35. Thesystem of claim 34, wherein the bioabsorbable material is selected fromthe group consisting of polylactic acid and polysulfone.
 36. The systemof claim 20, wherein the expansion pin is formed from a bioabsorbablematerial.
 37. The system of claim 36, wherein the bioabsorbable materialis selected from the group consisting of polylactic acid andpolysulfone.
 38. A suture anchor, comprising: a first componentincluding a tip having a suture thread-engaging groove formed therein,and a through-hole extending through the tip in a direction transverseto a longitudinal axis of the suture anchor; a second component havingan external surface with at least one positive surface feature formedthereon, at least a portion of the second component being selectivelyradially expandable; and a bore extending into the second component ofthe suture anchor from the proximal end thereof, the bore being parallelwith the longitudinal axis of the suture anchor.
 39. The suture anchorof claim 38, wherein the first component is separate from the secondcomponent.
 40. The suture anchor of claim 39, wherein the firstcomponent and the second component are threadingly engaged with eachother.
 41. The suture anchor of claim 39, wherein the bore extendsentirely through the second component of the suture anchor from aproximal end to a distal end thereof.
 42. The suture anchor of claim 41,wherein the at least one positive surface feature comprises a pluralityof wedge-like fins.
 43. The suture anchor of claim 42, wherein eachwedge-like fin has a ramped surface distal of a distal facing endwallthat is substantially transverse to the longitudinal axis of the sutureanchor.
 44. The suture anchor of claim 43, wherein the suture anchorfurther comprises a separate expansion element having an outsidediameter sufficient to fit within the bore of the second component in aninterference fit to cause the second component to radially expand. 45.The suture anchor of claim 44, wherein the external surface of theexpansion element has at least one positive surface feature effective toassist in the radial expansion of the second component from a firstdiameter to a second diameter.
 46. The suture anchor of claim 45,wherein the positive surface feature is a wedge-like structure having aproximal portion that is raised relative to a distal end thereof. 47.The suture anchor of claim 46, wherein a distal portion of the boreincludes internal threads.
 48. The suture anchor of claim 39, whereinthe tip is made from a material selected from the group consisting ofpolylactic acid and polysulfone.
 49. The suture anchor of claim 39,wherein the second component is made from a material selected from thegroup consisting of high density polyethylene and polypropylene.
 50. Thesuture anchor of claim 44, wherein the expansion element isbioabsorbable and is made from a material selected from the groupconsisting of polylactic acid and polysulfone.
 51. The suture anchor ofclaim 45, wherein the difference between the first diameter and thesecond diameter is in the range of about 1.0 to 1.5 mm.
 52. The sutureanchor of claim 38, wherein the first and second components of thesuture anchor are made from the same material and are integral with eachother.
 53. The suture anchor of claim 52, wherein a proximal end of thesecond component has longitudinally extending slits formed therein onopposite sides of the second component.
 54. The suture anchor of claim52, wherein the bore terminates proximal of the through-hole and doesnot communicate with the through-hole.
 55. The suture anchor of claim54, wherein the at least one positive surface feature comprises aplurality of wedge-like fins.
 56. The suture anchor of claim 55, whereineach wedge-like fin has a ramped surface distal of a distal facingendwall that is substantially transverse to the longitudinal axis of thesuture anchor.
 57. The suture anchor of claim 56, wherein the sutureanchor further comprises a separate expansion element having an outsidediameter sufficient to enable the expansion element to fit within thebore of the second component in an interference fit to effect radialexpansion of the second component from a first diameter to a seconddiameter.
 58. The suture anchor of claim 57, wherein the externalsurface of the expansion element has at least one positive surfacefeature effective to assist in the radial expansion of the secondcomponent from the first diameter to the second diameter.
 59. The sutureanchor of claim 58, wherein the expansion element has at least twopositive surface features on opposite sides of the expansion element andeach positive surface feature includes at least one wedge-like structurehaving a proximal portion that is raised relative to a distal endthereof.
 60. The suture anchor of claim 59, wherein each of the at leastone wedge-like structures is complementary in shape to the slits of thesuture anchor.
 61. The suture anchor of claim 59, wherein each of the atleast one wedge-like structures has dimensions that enable it to fitwithin and irreversibly interlock with the slits of the suture anchor.62. The suture anchor of claim 57, wherein the difference between thefirst diameter and the second diameter is in the range of about 1.0 to1.5 mm.
 63. The suture anchor of claim 52, wherein the suture anchor ismade from a material selected from the group consisting of high densitypolyethylene and polypropylene.
 64. The suture anchor of claim 57,wherein the expansion element is bioabsorbable.
 65. The suture anchor ofclaim 64, wherein the expansion element is made from a material selectedfrom the group consisting of polylactic acid and polysulfone.